BeagleBone mainline testing with buildroot

Background

We're getting close to getting BeagleBone support in the mainline [Linux kernel git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git] in good shape, but we still have quite a ways to go. By publishing the process I'm using for kernel testing, I'm hopeful others can step in and help improve the state of the kernel by reporting issues, reviewing patches and submitting both feature and bug fix patches to the appropriate staging trees.